Polycycloolefins can be prepared by solution ring opening polymerization of at least one cycloolefin that contains at least one norbornene group. The polymerization reaction yields a honey-like cement containing about 15% solids that comprises polymer solids dissolved in a solvent. The polymer is then precipitated and separated from the cement in a known manner.
The resulting polymer, that can be a homopolymer, copolymer, terpolymer, etc., is brittle and requires modification to make it suitable for commercial applications. For instance, notched Izod value of unmodified polymethyltetracyclodecedene is 44 J/M, which reflects the brittle character of the polymer and which for many applications is an unacceptably low impact strength resistance.
It is well known to use rubbery materials as impact modifiers in polymer systems. An attempt was initially made to use a conventional impact modifier for polycycloolefins, however, it proved dissappointing. Only a small improvement in toughness to 85 J/M was observed when 5 parts of a hydrogenated block copolymer of styrene-butadiene-styrene was dissolved in 5-methyltetracyclododecene and polymerized in bulk in the usual manner with a ring opening catalyst. The material was also observed to have a brittle character, as in the case of unmodified polymethyltetracyclododecene. Other conventional impact modifiers that were also tried were acrylonitrile-butadiene-styrene and methyl methacrylate-styrene-butadiene rubbery materials. These impact modifiers in polymethyltetracyclododecene resulted in negligible improvement in toughness to about 50 J/M.
This invention is an improvement over a companion application Ser. No. 427,369 filed on Sept. 29, 1982 for inventors DeWitt, Minchak, Lee and Benedikt entitled "Impact Modified Polycycloolefins" which discloses the use of polyolefin powders in excess of about 5 parts per 100 parts of the monomers as impact modifiers for polycycloolefins prepared by bulk polymerization. Although polyolefins have been used in the past as lubricants or slip agents in PVC and other polymer systems in amounts less than about 1%, the use of polyolefins in amount in excess of about 5 parts in polycycloolefins to obtain about a tripling of impact strength was totally unexpected.